<!DOCTYPE html>
<!--
     Any copyright is dedicated to the Public Domain.
     http://creativecommons.org/publicdomain/zero/1.0/
-->
<html>
<head>
  <title>
    CSS Reference
  </title>
  <style>
    .box {
      display: flex;
      border: 1px solid black;
      margin: 5px 20px;
    }

    .box > * {
      border: 1px dotted purple;
    }
  </style>
</head>
<body>
  <div class="box">
    <div>1</div>
    <div>0</div>
  </div>
</body>
</html>
